The present invention relates to a filler for packing machines of a type where a liquid product is metered into packing containers.
Modern packing machines for the packaging of liquid products, such as milk, fruit juices etc. in non-returnable packages of paper and plastics have a very high production capacity, and a rate of manufacture of 8000-10,000 packages per hour in a packaging line is not uncommon. The rate of packaging naturally depends to some extent on the size of the packages and it has been found that especially the so-called filling of liquid product by metering is a limiting factor for the capacity of packaging machines of the aforementioned type. Given the high rates of manufacture of packages as indicated above, the filling has to take place in an extremely short time, mostly fractions of a second, which makes great demands on the filling arrangements, and in particular the demand on volume accuracy of the packages is very high. One precondition for making it possible to achieve a filling in the short times which are available is that the filling should take place with little or no turbulence, without spill, splashing over and without formation of froth, that is without allowing air to interfere in the filling.
It is known that in packing machines of the aforementioned type, so-called piston fillers are used. That is to say cylinders are connected to the filling pipe wherein movable pistons are arranged by which the product is pressed out through the filling pipe and down into the packages. These piston fillers in many cases work satsifactorily, but they are relatively expensive and bulky and also relatively awkward to clean. Moreover, if piston fillers are used in e.g. a rotating filling machine with a number of filling pipes, a piston filler has to be assigned to each filling pipe, which as mentioned before will be expensive and bulky, especially since as a rule driving mechanisms for the piston fillers have to be provided at the rate of one mechanism for each piston filler.
A need exists, therefore, for a filler of a different kind and such a filler is described in the following and has the characteristics which are evident from the subsequent description.